The overall objective of this proposed research is to elucidate the mechanism by which initiation of protein synthesis occurs in eukaryotic organisms. One of our objectives is to identify and characterize all of the factors required for the initiation of translation of mRNA in wheat germ, determine the function of these factors in the initiation process, and how these factors are functionally related to the mammalian initiation factors. A second objective is to identify the factors required for the initiation of protein synthesis on yeast mitochondrial ribosomes and determine how these factors are functionally related to eukaryotic cytoplasmic initiation factors and to Escherichia coli initiation factors.